The present invention relates generally to inkjet printing systems, and more particularly to detection of an ink container leak in an inkjet printing system.
A conventional inkjet printing system includes a printhead and an ink supply which supplies liquid ink to the printhead. The printhead ejects ink drops through a plurality of orifices or nozzles and toward a print medium, such as a sheet of paper, so as to print a dot of ink on the print medium. Typically, the orifices are arranged in one or more arrays such that properly sequenced ejection of ink from the orifices causes characters or other images to be printed upon the print medium as the printhead and the print medium are moved relative to each other. In one arrangement, commonly referred to as xe2x80x9con-axisxe2x80x9d printing, the ink supply is an integral element with the printhead. In another arrangement, however, commonly referred to as xe2x80x9coff-axisxe2x80x9d printing, the ink supply is a separate, self-contained ink container connected with the printhead by, for example, a flexible tube. With an off-axis printing system, the mass of the printhead is sharply reduced such that the cost of a printhead drive system and an overall size of a printer can be minimized, and a speed of printing can be increased. In addition, separating the ink supply from the printhead allows the ink to be replaced as it is consumed without requiring replacement of the costly printhead.
A conventional self-contained ink container for an off-axis printing system typically includes a housing and a collapsible ink reservoir, in the form of a bladder or bag, disposed within the housing for holding a supply of liquid ink therein. As such, a pressurized air system releases pressurized air into the housing and around the ink reservoir to collapse the ink reservoir and deliver ink to the printhead. The potential exists, however, for the collapsible ink reservoir to develop a leak. The leak could result, for example, from a pin hole in the collapsible ink reservoir, a rupture of the collapsible ink reservoir, and/or a defective seal of the collapsible ink reservoir. Unfortunately, if a leak does develop, air from the pressurized air system could enter the collapsible ink reservoir. As such, air in the collapsible ink reservoir could be drawn into the printhead thereby causing damage to the printhead. Furthermore, if a leak does develop, ink can escape from the collapsible ink reservoir. If the ink container is installed with the printing system, ink escaping from the collapsible ink reservoir can enter and contaminate the pressurized air system. If the ink container is separate from the printing system, ink escaping from the collapsible ink reservoir can spill from the housing.
Accordingly, a need exists for detection of a leak of a collapsible ink reservoir of an ink container such that the potential for drawing air into a printhead through the collapsible ink reservoir is avoided and/or complications caused by ink escaping from the collapsible ink reservoir are avoided.
One aspect of the present invention provides a printing system including a printhead, an ink container communicating with and supplying liquid ink to the printhead, and a leak indicator communicating with and indicating an ink container leak based on a pressure of liquid ink supplied to the printhead and a volume of liquid ink supplied to the printhead.
In one embodiment, the leak indicator indicates the ink container leak when the pressure of liquid ink supplied to the printhead is less than a predetermined value and the volume of liquid ink supplied to the printhead is greater than a predetermined value. In one embodiment, the volume of liquid ink supplied to the printhead is derived from a count of a number of drops of the liquid ink ejected from the printhead.
In one embodiment, a pressurized source of gas communicates with and supplies pressurized gas to the ink container so as to pressurize the ink container and expel liquid ink from the ink container during printing. As such, the pressure of liquid ink supplied to the printhead is based on a differential pressure of liquid ink supplied to the printhead and pressurized gas supplied to the ink container.
Another aspect of the present invention provides a printing system including an ink container adapted to hold a supply of liquid ink therein, a first flow path communicating with the ink container and the supply of liquid ink, and a printhead communicating with the first flow path. A pressure sensor communicates with the first flow path and measures a pressure of liquid ink disposed therein, and a volume detector communicates with the first flow path and detects a volume of liquid ink delivered therethrough. A leak indicator communicates with the pressure sensor and the volume detector, and indicates an ink container leak based on the pressure of liquid ink disposed in the first flow path and the volume of liquid ink delivered through the first flow path.
Another aspect of the present invention provides a method of detecting an ink container leak of an ink container adapted to hold a supply of liquid ink therein. The method includes the steps of pressurizing the ink container to expel liquid ink therefrom, measuring a pressure of liquid ink expelled from the ink container, measuring a volume of liquid ink expelled from the ink container, and indicating the ink container leak based on the pressure of liquid ink expelled from the ink container and the volume of liquid ink expelled from the ink container.
Another aspect of the present invention provides a printing system including a housing having walls defining an interior chamber adapted to hold a supply of liquid ink therein such that the supply of liquid ink defines an occupied portion and an unoccupied portion of the interior chamber. A first flow path communicates with the occupied portion of the interior chamber of the housing and externally of the housing, and a second flow path communicates with the unoccupied portion of the interior chamber of the housing and externally of the housing. As such, the first flow path is adapted to deliver liquid ink therethrough and the second flow path is adapted to receive pressurized gas therethrough. In addition, a pressure sensor communicates with and is adapted to measure a pressure of liquid ink delivered through the first flow path.
Another aspect of the present invention provides a printing system including a housing defining an interior chamber and a collapsible reservoir disposed within the interior chamber, wherein the collapsible reservoir is adapted to hold a supply of liquid ink therein. A first flow path communicates with the collapsible reservoir and externally of the housing, and a second flow path communicates with the interior chamber of the housing and externally of the housing. As such, the first flow path is adapted to deliver liquid ink therethrough and the second flow path is adapted to receive pressurized gas therethrough. In addition, a pressure sensor communicates with and is adapted to measure a pressure of liquid ink delivered through the first flow path.
The present invention provides a printing system which includes detection of an ink container leak in the printing system and, more specifically, detection of a leak in a collapsible ink reservoir of an ink container in the printing system. As such, the potential for drawing air into a printhead of the printing system through the ink container leak is avoided and/or complications caused by ink escaping from the collapsible ink reservoir are avoided.